Physical Vapor Deposition Processing Systems Target Cooling

ABSTRACT

Physical vapor deposition target assemblies and methods of manufacturing such target assemblies are disclosed. An exemplary target assembly comprises a flow pattern including a plurality of arcs and bends fluidly connected to an inlet end and an outlet end.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/867,878, filed May 6, 2020, which is a continuation of U.S. patentapplication Ser. No. 15/680,975, filed Aug. 18, 2017, now U.S. Pat. No.10,685,821, issued Jun. 16, 2020, the subject matter thereofincorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates generally to substrate processingsystems, and more specifically, to physical vapor deposition (PVD)processing systems.

BACKGROUND

Sputtering, alternatively called physical vapor deposition (PVD), haslong been used in depositing metals and related materials in thefabrication of semiconductor integrated circuits. Use of sputtering hasbeen extended to depositing metal layers onto the sidewalls of highaspect-ratio holes such as vias or other vertical interconnectstructures, as well as in the manufacture of extreme ultraviolet (EUV)mask blanks. In the manufacture of EUV mask blanks minimization ofparticle generation is desired, because particles negatively impact theproperties of the final product.

Plasma sputtering may be accomplished using either DC sputtering or RFsputtering. Plasma sputtering typically includes a magnetron positionedat the back of the sputtering target to project a magnetic field intothe processing space to increase the density of the plasma and enhancethe sputtering rate. Magnets used in the magnetron are typically closedloop for DC sputtering and open loop for RF sputtering.

In plasma enhanced substrate processing systems, such as physical vapordeposition (PVD) chambers, high power density PVD sputtering with highmagnetic fields and high DC Power can produce high energy at asputtering target, and cause a large rise in surface temperature of thesputtering target. The sputtering target is cooled by contacting atarget backing plate with cooling fluid. However, it has been determinedthat such cooling may not be sufficient to capture and remove heat fromthe target. Remaining heat in the target can result in significantmechanical bowing due to thermal gradient in the sputter material andacross backing plate. The mechanical bowing increases as larger sizewafers are being processed. This additional size aggravates the tendencyof the target to bow/deform under thermal, pressure and gravitationalloads. The impacts of bowing may include mechanical stress induced inthe target material that can lead to fracture, damage to the target, andchanges in distance from a magnet assembly to the face of the targetmaterial that can cause changes in the plasma properties (e.g., movingthe processing regime out of an optimal or desired processing conditionwhich affects the ability to maintain plasma, sputter/deposition rate,and erosion of the target).

In addition, higher target temperature results in re-sputtering oftarget material, which causes particle generation and defects on otherparts of the PVD chamber and the wafer being processed in the chamber.The thermal management of target cooling is important not only fortarget life but also for reducing particles and defects, which willimprove process yield. There is need to provide apparatus and methods toefficiently cool PVD targets during physical vapor deposition processes.

SUMMARY

One or more embodiments of the disclosure are directed to a physicalvapor deposition target assembly comprising a source material; a backingplate having a front side and a back side, the backing plate configuredto support the source material on a front side of the backing plate; anda cooling channel formed in the backing plate including an inlet endconfigured to be connected to a cooling fluid, an outlet end fluidlycoupled to the inlet end, and the cooling channel comprising a pluralityof arcs joined together by a plurality of bends between the inlet endand the outlet end, the backing plate configured to cool the sourcematerial during a physical vapor deposition process.

Another aspect of the disclosure pertains to a method of manufacturing aphysical vapor deposition target assembly comprising forming a backingplate having a front side and a back side, the backing plate configuredto support a source material on a front side of the backing plate; andforming a cooling channel in the backing plate including an inlet endconfigured to be connected to cooling fluid, an outlet end fluidlycoupled to the inlet end, and the cooling channel comprising a pluralityof arcs joined together by a plurality of bends between the inlet endand the outlet end, the backing plate configured to be to cool thesource material during a physical vapor deposition process

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentdisclosure can be understood in detail, a more particular description ofthe disclosure, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings. Itis to be noted, however, that the appended drawings illustrate onlytypical embodiments of this disclosure and are therefore not to beconsidered limiting of its scope, for the disclosure may admit to otherequally effective embodiments.

FIG. 1 depicts a schematic cross-sectional view of a process chamber inaccordance with some embodiments of the present disclosure;

FIG. 2 illustrates a perspective view of prior art target assembly;

FIG. 3 illustrates a cross-sectional view taken along line 3-3 of FIG.2;

FIG. 4 illustrates a cross-sectional view of a prior art targetassembly;

FIG. 5 illustrates a perspective view of a target assembly according toan embodiment;

FIG. 6 illustrates a cross-sectional view taken along line 6-6 of FIG.5;

FIG. 7A illustrates a cross-sectional view of target assembly accordingto an embodiment;

FIG. 7B illustrates a cross-sectional view of target assembly accordingto an embodiment;

FIG. 7C illustrates a cross-sectional view of target assembly accordingto an embodiment;

FIG. 8 illustrates channels defining a flow pattern according to anembodiment;

FIG. 9 illustrates an exploded perspective view of a target assemblyaccording to an embodiment; and

FIG. 10 illustrates a multi-cathode PVD deposition chamber according toan embodiment.

DETAILED DESCRIPTION

Before describing several exemplary embodiments of the disclosure, it isto be understood that the disclosure is not limited to the details ofconstruction or process steps set forth in the following description.The disclosure is capable of other embodiments and of being practiced orbeing carried out in various ways.

The term “horizontal” as used herein is defined as a plane parallel tothe plane or surface of a mask blank, regardless of its orientation. Theterm “vertical” refers to a direction perpendicular to the horizontal asjust defined. Terms, such as “above”, “below”, “bottom”, “top”, “side”(as in “sidewall”), “higher”, “lower”, “upper”, “over”, and “under”, aredefined with respect to the horizontal plane, as shown in the figures.

The term “on” indicates that there is direct contact between elements.The term “directly on” indicates that there is direct contact betweenelements with no intervening elements.

As used in this specification and the appended claims, the terms“precursor”, “reactant”, “reactive gas” and the like are usedinterchangeably to refer to any gaseous species that can react with thesubstrate surface.

Those skilled in the art will understand that the use of ordinals suchas “first” and “second” to describe process regions do not imply aspecific location within the processing chamber, or order of exposurewithin the processing chamber.

FIG. 1 depicts a simplified, cross-sectional view of a physical vapordeposition (PVD) processing system 100 in accordance with someembodiments of the present disclosure. Examples of other PVD chamberssuitable for modification in accordance with the teachings providedherein include the ALPS® Plus and SIP ENCORE® PVD processing chambers,both commercially available from Applied Materials, Inc., of SantaClara, Calif. Other processing chambers from Applied Materials, Inc. orother manufactures, including those configured for other types ofprocessing besides PVD, may also benefit from modifications inaccordance with the teachings disclosed herein.

In some embodiments of the present disclosure, the PVD processing system100 includes a chamber body 101 removably disposed atop a processchamber 104. The chamber body 101 may include a target assembly 114 anda grounding assembly 103. The process chamber 104 contains a substratesupport 106 for receiving a substrate 108 thereon. The substrate support106 may be located within a lower grounded enclosure wall 110, which maybe a chamber wall of the process chamber 104. The lower groundedenclosure wall 110 may be electrically coupled to the grounding assembly103 of the chamber body 101 such that an RF return path is provided toan RF or DC power source 182 disposed above the chamber body 101. The RFor DC power source 182 may provide RF or DC power to the target assembly114 as discussed below.

The substrate support 106 has a material-receiving surface facing aprincipal surface of a target assembly 114 and supports the substrate108 to be sputter coated in planar position opposite to the principalsurface of the target assembly 114. The substrate support 106 maysupport the substrate 108 in a central region 120 of the process chamber104. The central region 120 is defined as the region above the substratesupport 106 during processing (for example, between the target assembly114 and the substrate support 106 when in a processing position).

In some embodiments, the substrate support 106 may be vertically movableto allow the substrate 108 to be transferred onto the substrate support106 through a load lock valve (not shown) in the lower portion of theprocess chamber 104 and thereafter raised to a deposition, or processingposition. A bellows 122 connected to a bottom chamber wall 124 may beprovided to maintain a separation of the inner volume of the processchamber 104 from the atmosphere outside of the process chamber 104 whilefacilitating vertical movement of the substrate support 106. One or moregases may be supplied from a gas source 126 through a mass flowcontroller 128 into the lower part of the process chamber 104. Anexhaust port 130 may be provided and coupled to a pump (not shown) via avalve 132 for exhausting the interior of the process chamber 104 and tofacilitate maintaining a desired pressure inside the process chamber104.

An RF bias power source 134 may be coupled to the substrate support 106in order to induce a negative DC bias on the substrate 108. In addition,in some embodiments, a negative DC self-bias may form on the substrate108 during processing. For example, RF energy supplied by the RF biaspower source 134 may range in frequency from about 2 MHz to about 60MHz, for example, non-limiting frequencies such as 2 MHz, 13.56 MHz, or60 MHz can be used. In other applications, the substrate support 106 maybe grounded or left electrically floating. Alternatively or incombination, a capacitance tuner 136 may be coupled to the substratesupport 106 for adjusting voltage on the substrate 108 for applicationswhere RF bias power may not be desired.

The process chamber 104 further includes a process kit shield, or shield138 to surround the processing volume, or central region 120 of theprocess chamber 104 and to protect other chamber components from damageand/or contamination from processing. In some embodiments, the shield138 may be connected to a ledge 140 of an upper grounded enclosure wall116 of the process chamber 104. As illustrated in FIG. 1, the chamberbody 101 may rest on the ledge 140 of the upper grounded enclosure wall116. Similar to the lower grounded enclosure wall 110, the uppergrounded enclosure wall 116 may provide a portion of the RF return pathbetween the lower grounded enclosure wall 116 and the grounding assembly103 of the chamber body 101. However, other RF return paths arepossible, such as via the grounded shield 138.

The shield 138 extends downwardly and may include a generally tubularportion having a generally constant diameter that generally surroundsthe central region 120. The shield 138 extends along the walls of theupper grounded enclosure wall 116 and the lower grounded enclosure wall110 downwardly to below a top surface of the substrate support 106 andreturns upwardly until reaching a top surface of the substrate support106 (e.g., forming a u-shaped portion at the bottom of the shield 138).A cover ring 148 rests on the top of an upwardly extending inner portionof the shield 138 when the substrate support 106 is in its lower,loading position but rests on the outer periphery of the substratesupport 106 when it is in its upper, deposition position to protect thesubstrate support 106 from sputter deposition. An additional depositionring (not shown) may be used to protect the edges of the substratesupport 106 from deposition around the edge of the substrate 108.

In some embodiments, a magnet 152 may be disposed about the processchamber 104 to selectively provide a magnetic field between thesubstrate support 106 and the target assembly 114. For example, as shownin FIG. 1, the magnet 152 may be disposed about the outside of theenclosure wall 110 in a region just above the substrate support 106 whenin processing position. In some embodiments, the magnet 152 may bedisposed additionally or alternatively in other locations, such asadjacent the upper grounded enclosure wall 116. The magnet 152 may be anelectromagnet and may be coupled to a power source (not shown) forcontrolling the magnitude of the magnetic field generated by theelectromagnet.

The chamber body 101 generally includes the grounding assembly 103disposed about the target assembly 114. The grounding assembly 103 mayinclude a grounding plate 156 having a first surface 157 that may begenerally parallel to and opposite a backside of the target assembly114. A grounding shield 112 may extend from the first surface 157 of thegrounding plate 156 and surround the target assembly 114. The groundingassembly 103 may include a support member 175 to support the targetassembly 114 within the grounding assembly 103.

In some embodiments, the support member 175 may be coupled to a lowerend of the grounding shield 112 proximate an outer peripheral edge ofthe support member 175 and extends radially inward to support a sealring 181, the target assembly 114 and optionally, a dark space shield179. The seal ring 181 may be a ring or other annular shape having adesired cross-section. The seal ring 181 may include two opposing planarand generally parallel surfaces to facilitate interfacing with thetarget assembly 114, such as the backing plate assembly 160, on a firstside of the seal ring 181 and with the support member 175 on a secondside of the seal ring 181. The seal ring 181 may be made of a dielectricmaterial, such as ceramic. The seal ring 181 may insulate the targetassembly 114 from the ground assembly 103.

The dark space shield 179 is generally disposed about an outer edge ofthe target assembly 114, such about an outer edge of a source material113 of the target assembly 114. In some embodiments, the seal ring 181is disposed adjacent to an outer edge of the dark space shield 179(i.e., radially outward of the dark space shield 179). In someembodiments, the dark space shield 179 is made of a dielectric material,such as ceramic. By providing a dark space shield 179, arcing betweenthe dark space shield and adjacent components that are RF hot may beavoided or minimized. Alternatively, in some embodiments, the dark spaceshield 179 is made of a conductive material, such as stainless steel,aluminum, or the like. By providing a conductive dark space shield 179 amore uniform electric field may be maintained within the PVD processingsystem 100, thereby promoting more uniform processing of substratestherein. In some embodiments, a lower portion of the dark space shield179 may be made of a conductive material and an upper portion of thedark space shield 179 may be made of a dielectric material.

The support member 175 may be a generally planar member having a centralopening to accommodate the dark space shield 179 and the target assembly114. In some embodiments, the support member 175 may be circular, ordisc-like in shape, although the shape may vary depending upon thecorresponding shape of the chamber lid and/or the shape of the substrateto be processed in the PVD processing system 100. In use, when thechamber body 101 is opened or closed, the support member 175 maintainsthe dark space shield 179 in proper alignment with respect to the targetassembly 114, thereby minimizing the risk of misalignment due to chamberassembly or opening and closing the chamber body 101.

The PVD processing system 100 may include a source distribution plate158 opposing a backside of the target assembly 114 and electricallycoupled to the target assembly 114 along a peripheral edge of the targetassembly 114. The target assembly 114 may comprise a source material 113to be deposited on a substrate, such as the substrate 108 duringsputtering, such as a metal, metal oxide, metal alloy, or the like. Inone or more embodiments, the target assembly 114 includes a backingplate assembly 160 to support the source material 113. The sourcematerial 113 may be disposed on a substrate support facing side of thebacking plate assembly 160 as illustrated in FIG. 1. The backing plateassembly 160 may comprise a conductive material, such as copper-zinc,copper-chrome, or the same material as the target, such that RF and DCpower can be coupled to the source material 113 via the backing plateassembly 160. Alternatively, the backing plate assembly 160 may benon-conductive and may include conductive elements (not shown) such aselectrical feedthroughs or the like.

In one or more embodiments, the backing plate assembly 160 includes abacking plate 161 and a cover plate 162. The backing plate 161 and thecover plate 162 may be disc shaped, rectangular, square, or any othershape that may be accommodated by the PVD processing system 100. A frontside of the backing plate is configured to support the source material113 such that a front surface of the source material opposes thesubstrate 108 when present. The source material 113 may be coupled tothe backing plate 161 in any suitable manner. For example, in someembodiments, the source material 113 may be diffusion bonded to thebacking plate 161.

A plurality of channels 169 may be disposed between the backing plate161 and the cover plate 162. In one or more embodiments, the backingplate 161 may have the plurality of channels 169 formed in a backside ofthe backing plate 161 with the cover plate 162 providing a cap/coverover each of the channels. In other embodiments, the plurality ofchannels 169 may be formed partially in the backing plate 161 andpartially in the cover plate 162. Still, in other embodiments, theplurality of channels 169 may be formed entirely in the cover plate 162,while the backing plate caps/covers each of the plurality of channels169. The backing plate 161 and the cover plate 162 may be coupledtogether.

In some embodiments, the cover plate 162 is eliminated, and the backingplate 161 is a monolithic material. Such a backing plate 161 ofmonolithic material can be formed by 3D printing, and the plurality ofchannels 169 are formed during the 3D printing process. In someembodiments, the plurality of channels 169 are configured to flowcooling fluid, and the backing plate 161 and the cover plate 162 arecoupled together to form a substantially water tight seal (e.g., a fluidseal between the backing plate 161 and the cover plates 162) to preventleakage of coolant provided to the plurality of channels 169. That is,the cooling fluid is in direct contact with the channels 169. Forexample, in some embodiments, the backing plate 161 and the cover plate162 are brazed together to form a substantially water tight seal or theymay be coupled by diffusion bonding, brazing, gluing, pinning, riveting,or any other fastening means to provide a liquid seal, and the channels169 formed between the backing plate 161 and the cover plate 162directly contact cooling fluid. However, in other embodiments, thebacking plate 161 has the plurality of channels 169 machined therein.The cover plate 162 is then optionally machined (or not machined).Brazing paste is placed between the backing plate 161 and the coverplate 162. Electron beam (E-beam) welding is then utilized to fasten thebacking plate 161 and the cover plate 162 together. Thereafter, thefastened components can be heated to complete the fastening process, andthen the fastened components may be machined to the final tolerance andspecifications. Then the source material in the form of a target can bebonded to the backing plate 161 or cover plate 162 with indium solder.As will be described further below, according to some embodiments of theinstant disclosure, a fluid tight seal between the backing plate 161 andthe cover plate 162 is not necessary because the cooling fluid iscontained within tubing which is disposed within the channels 169.

The backing plate 161 and the cover plate 162 may comprise anelectrically conductive material, such as an electrically conductivemetal or metal alloy including brass, aluminum, copper, aluminum alloys,copper alloys, or the like. In some embodiments, the backing plate 161may be a machinable metal or metal alloy (e.g., C18200 chromium copperalloy) such that the channels may be machined or otherwise created on asurface of the backing plate 161. In some embodiments, the cover plate162 may be a machinable metal or metal alloy, (e.g., C18200 chromiumcopper alloy) having a stiffness/elastic modulus greater than the metalor metal alloy of the backing plate to provide improved stiffness andlower deformation of backing plate assembly 160. The materials and sizesof the backing plate 161 and the cover plate 162 should be such that thestiffness of the entire backing plate assembly 160 will withstand thevacuum, gravitational, thermal, and other forces exerted on the targetassembly 114 during deposition process, without (or with very little)deformation or bowing of the target assembly 114 including the sourcematerial 113 (i.e., such that the front of surface source material 113remains substantially parallel to the top surface of a substrate 108).

In some embodiments, the overall thickness of the target assembly 114may be between about 20 mm to about 100 mm. For example, the sourcematerial 113 may be about 10 to about 15 mm thick and the backing plateassembly may be about 10 to about 30 mm thick. Other thicknesses mayalso be used.

The plurality of channels 169 may include one or more sets of channels(discussed in detail below). For example, in some exemplary embodimentsthere may one set of channels. In other embodiments, there may two ormore sets of channels. The size and cross-sectional shape of eachchannel, as well as the number of channels in each set and number ofchannels may be optimized based on one or more of the followingcharacteristics: to provide a desired maximum flow rate through thechannel and in total through all channels; to provide maximum heattransfer characteristics; ease and consistency in manufacturing channelswithin the backing plate 161 and the cover plate 162; to provide themost heat exchange flow coverage over the surfaces of the backing plateassembly 160 while retaining enough structural integrity to preventdeformation of the backing plate assembly 160 under load, etc. In someembodiments, the cross-sectional shape of each channel may berectangular, polygonal, elliptical, circular, and the like.

In some embodiments, the target assembly includes one or more inlets(not shown in FIG. 1 and discussed in detail below) fluidly coupled withthe channels 169 or with tubing. The one or more inlets are configuredto receive a heat exchange fluid and to provide the heat exchange fluidto the plurality of channels 169 or to the tubing. For example, at leastone of the one or more inlets may be a plenum to distribute the heatexchange fluid to the plurality of channels 169 or to tubing. Theassembly further includes one or more outlets (not shown in FIG. 1 anddiscussed in detail below) disposed through the cover plate 162 andfluidly coupled to a corresponding inlet by the plurality of channels169 or tubing. For example, at least one of the one or more outlets maybe a plenum to collect the heat exchange fluid from a plurality of theone or more channels or tubing. In some embodiments, one inlet and oneoutlet are provided and each set of channels in the plurality of set ofchannels 169 is fluidly coupled to the one inlet and the one outlet.

The inlets and outlets may be disposed on or near a peripheral edge ofthe cover plate 162 or backing plate 161. In addition, the inlets andoutlets may be disposed on the cover plate 162 such that supply conduits167 coupled to the one or more inlets, and return conduits coupled tothe one or more outlets, do not interfere with the rotation of amagnetron assembly 196 in cavity 170. In other embodiments, the inletsand outlets may be disposed on the backing plate 161 such that supplyconduits 167 coupled to the one or more inlets, and return conduits (notshown due to cross section) coupled to the one or more outlets, do notinterfere with the rotation of a magnetron assembly 196 in cavity 170.In still other embodiments, the inlets and outlets may be coupled totubing such that supply conduits 167 coupled to the one or more inlets,and return conduits (not shown due to cross section), coupled to the oneor more outlets, do not interfere with the rotation of a magnetronassembly 196 in cavity 170.

In some embodiments, PVD processing system 100 may include one or moresupply conduits 167 to supply heat exchange fluid to the backing plateassembly 160. In some embodiments, each inlet may be coupled to acorresponding supply conduit 167. Similarly, each outlet may be coupledto a corresponding return conduit. Supply conduits 167 and returnconduits may be made of insulating materials. The supply conduit 167 mayinclude a seal ring (e.g., a compressible o-ring or similar gasketmaterial) to prevent heat exchange fluid leakage between the supplyconduit 167 and an inlet. In some embodiments, a top end of supplyconduits 167 may be coupled to a fluid distribution manifold 163disposed on the top surface of the chamber body 101. The fluiddistribution manifold 163 may be fluidly coupled to the plurality ofsupply conduits 167 to supply heat exchange fluid to each of theplurality of supply conduits via supply lines 165. Similarly, a top endof return conduits may be coupled to a return fluid manifold (not shown,but similar to 163) disposed on the top surface of the chamber body 101.The return fluid manifold may be fluidly coupled to the plurality ofreturn conduits to return heat exchange fluid from each of the pluralityof return conduits via return lines.

The fluid distribution manifold 163 may be coupled to a heat exchangefluid source (not shown) to provide a heat exchange fluid in the form ofa liquid to the backing plate assembly 160. The heat exchange fluid maybe any process compatible liquid coolant, such as ethylene glycol,deionized water, a perfluorinated polyether (such as Golden®, availablefrom Solvay S. A.), or the like, or solutions or combinations thereof.In some embodiments, the flow of coolant through the channels 169 ortubing may be about 8 to about 20 gallons per minute, in sum total,although the exact flows will depend upon the configuration of thecoolant channels, available coolant pressure, or the like.

A conductive support ring 164, having a central opening, is coupled to abackside of the cover plate 162 along a peripheral edge of the coverplate 162. In some embodiments, in place of separate supply and returnconduits, the conductive support ring 164 may include a ring inlet toreceive heat exchange fluid from a fluid supply line (not shown). Theconductive support ring 164 may include an inlet manifold, disposedwithin the body of the conductive support ring 164, to distribute theheat exchange fluid to an inlet connected to tubing or the channels 169.The conductive support ring 164 may include an outlet manifold, disposedwithin the body of the conductive support ring 164, to receive the heatexchange fluid from one or more outlets, and a ring outlet to output theheat exchange fluid from the conductive support ring 164. The conductivesupport ring 164 and the backing plate assembly 160 may be threadedtogether, pinned, bolted, or fastened in a process compatible manner toprovide a liquid seal between the conductive support ring 164 and thecover plate 162. O-rings or other suitable gasket materials may beprovided to facilitate providing a seal between the conductive supportring 164 and the cover plate 162.

In some embodiments, the target assembly 114 may further comprise acentral support member 192 to support the target assembly 114 within thechamber body 101. The central support member 192 may be coupled to acenter portion of the backing plate 161 and the cover plate 162 andextend perpendicularly away from the backside of the cover plate 162. Insome embodiments, a bottom portion of the central support member 192 maybe threaded into a central opening in the backing plate 161 and thecover plate 162. In other embodiments, a bottom portion of the centralsupport member 192 may be bolted or clamped to a central portion of thebacking plate 161 and the cover plate 162. A top portion of the centralsupport member 192 may be disposed through the source distribution plate158 and includes a feature which rests on a top surface of the sourcedistribution plate 158 that supports the central support member 192 andtarget assembly 114.

In some embodiments, the conductive support ring 164 may be disposedbetween the source distribution plate 158 and the backside of the targetassembly 114 to propagate RF energy from the source distribution plateto the peripheral edge of the target assembly 114. The conductivesupport ring 164 may be cylindrical, with a first end 166 coupled to atarget-facing surface of the source distribution plate 158 proximate theperipheral edge of the source distribution plate 158 and a second end168 coupled to a source distribution plate-facing surface of the targetassembly 114 proximate the peripheral edge of the target assembly 114.In some embodiments, the second end 168 is coupled to a sourcedistribution plate facing surface of the backing plate assembly 160proximate the peripheral edge of the backing plate assembly 160.

The PVD processing system 100 may include a cavity 170 disposed betweenthe backside of the target assembly 114 and the source distributionplate 158. The cavity 170 may at least partially house the magnetronassembly 196 as discussed below. The cavity 170 is at least partiallydefined by the inner surface of the conductive support ring 164, atarget facing surface of the source distribution plate 158, and a sourcedistribution plate facing surface (e.g., backside) of the targetassembly 114 (or backing plate assembly 160).

An insulative gap 180 is provided between the grounding plate 156 andthe outer surfaces of the source distribution plate 158, the conductivesupport ring 164, and the target assembly 114 (and/or backing plateassembly 160). The insulative gap 180 may be filled with air or someother suitable dielectric material, such as a ceramic, a plastic, or thelike. The distance between the grounding plate 156 and the sourcedistribution plate 158 depends on the dielectric material between thegrounding plate 156 and the source distribution plate 158. Where thedielectric material is predominantly air, the distance between thegrounding plate 156 and the source distribution plate 158 may be betweenabout 15 mm and about 40 mm.

The grounding assembly 103 and the target assembly 114 may beelectrically separated by the seal ring 181 and by one or more ofinsulators (not shown) disposed between the first surface 157 of thegrounding plate 156 and the backside of the target assembly 114, e.g., anon-target facing side of the source distribution plate 158.

The PVD processing system 100 has an RF or DC power source 182 connectedto an electrode 154 (e.g., a RF feed structure). The electrode 154 maypass through the grounding plate 156 and is coupled to the sourcedistribution plate 158. The RF or DC power source 182 may include an RFgenerator and a matching circuit, for example, to minimize reflected RFenergy reflected back to the RF generator during operation. For example,RF energy supplied by the RF or DC power source 182 may range infrequency from about 13.56 MHz to about 162 MHz or above. For example,non-limiting frequencies such as 13.56 MHz, 27.12 MHz, 40.68 MHz, 60MHz, or 162 MHz can be used.

In some embodiments, the PVD processing system 100 may include a secondenergy source 183 to provide additional energy to the target assembly114 during processing. In some embodiments, the second energy source 183may be a DC power source to provide DC energy, for example, to enhance asputtering rate of the target material (and hence, a deposition rate onthe substrate). In some embodiments, the second energy source 183 may bea second RF power source, similar to the RF or DC power source 182, toprovide RF energy, for example, at a second frequency different than afirst frequency of RF energy provided by the RF or DC power source 182.In embodiments where the second energy source 183 is a DC power source,the second energy source may be coupled to target assembly 114 in anylocation suitable to electrically couple the DC energy to the targetassembly 114, such as the electrode 154 or some other conductive member(such as the source distribution plate 158, discussed below). Inembodiments where the second energy source 183 is a second RF powersource, the second energy source may be coupled to the target assembly114 via the electrode 154.

The electrode 154 may be cylindrical or otherwise rod-like and may bealigned with a central axis 186 of the PVD processing system 100 (e.g.,the electrode 154 may be coupled to the target assembly at a pointcoincident with a central axis of the target, which is coincident withthe central axis 186). The electrode 154, aligned with the central axis186 of the PVD processing system 100, facilitates applying RF energyfrom the RF or DC power source 182 to the target assembly 114 in anaxisymmetrical manner (e.g., the electrode 154 may couple RF energy tothe target at a single point aligned with the central axis of the PVDchamber). The central position of the electrode 154 helps to eliminateor reduce deposition asymmetry in substrate deposition processes. Theelectrode 154 may have any suitable diameter. For example, althoughother diameters may be used, in some embodiments, the diameter of theelectrode 154 may be about 0.5 to about 2 inches. The electrode 154 maygenerally have any suitable length depending upon the configuration ofthe PVD chamber. In some embodiments, the electrode may have a length ofbetween about 0.5 to about 12 inches. The electrode 154 may befabricated from any suitable conductive material, such as aluminum,copper, silver, or the like. Alternatively, in some embodiments, theelectrode 154 may be tubular. In some embodiments, the diameter of thetubular electrode 154 may be suitable, for example, to facilitateproviding a central shaft for the magnetron.

The electrode 154 may pass through the ground plate 156 and is coupledto the source distribution plate 158. The ground plate 156 may compriseany suitable conductive material, such as aluminum, copper, or the like.The open spaces between the one or more insulators (not shown) allow forRF wave propagation along the surface of the source distribution plate158. In some embodiments, the one or more insulators may besymmetrically positioned with respect to the central axis 186 of the PVDprocessing system. Such positioning may facilitate symmetric RF wavepropagation along the surface of the source distribution plate 158 and,ultimately, to a target assembly 114 coupled to the source distributionplate 158. The RF energy may be provided in a more symmetric and uniformmanner as compared to conventional PVD chambers due, at least in part,to the central position of the electrode 154.

One or more portions of a magnetron assembly 196 may be disposed atleast partially within the cavity 170. The magnetron assembly provides arotating magnetic field proximate the target to assist in plasmaprocessing within the chamber body 101. In some embodiments, themagnetron assembly 196 may include a motor 176, a motor shaft 174, agear box 178, a gear box shaft assembly 184, and a rotatable magnet(e.g., a plurality of magnets 188 coupled to a magnet support member172), and divider 194. In some embodiments, the magnetron assembly 196remains stationary.

In some embodiments, the magnetron assembly 196 is rotated within thecavity 170. For example, in some embodiments, the motor 176, motor shaft174, gear box 178, and gear box shaft assembly 184 may be provided torotate the magnet support member 172. In conventional PVD chambershaving magnetrons, the magnetron drive shaft is typically disposed alongthe central axis of the chamber, preventing the coupling of RF energy ina position aligned with the central axis of the chamber. In one or moreembodiments, the electrode 154 is aligned with the central axis 186 ofthe PVD chamber. As such, in some embodiments, the motor shaft 174 ofthe magnetron may be disposed through an off-center opening in theground plate 156. The end of the motor shaft 174 protruding from theground plate 156 is coupled to a motor 176. The motor shaft 174 isfurther disposed through a corresponding off-center opening through thesource distribution plate 158 (e.g., a first opening 146) and coupled toa gear box 178. In some embodiments, one or more second openings (notshown) may be disposed though the source distribution plate 158 in asymmetrical relationship to the first opening 146 to advantageouslymaintain axisymmetric RF distribution along the source distributionplate 158. The one or more second openings may also be used to allowaccess to the cavity 170 for items such as optical sensors or the like.In one or more embodiments, the backing plate assemblies describedherein are particularly useful in multi-cathode PVD systems withrotating magnets. Prior art designs with larger cooling cavities limitedthe ability to utilize rotating magnets.

The gear box 178 may be supported by any suitable means, such as bybeing coupled to a bottom surface of the source distribution plate 158.The gear box 178 may be insulated from the source distribution plate 158by fabricating at least the upper surface of the gear box 178 from adielectric material, or by interposing an insulator layer (not shown)between the gear box 178 and the source distribution plate 158, or thelike, or by constructing the motor shaft 174 out of a suitabledielectric material. The gear box 178 is further coupled to the magnetsupport member 172 via the gear box shaft assembly 184 to transfer therotational motion provided by the motor 176 to the magnet support member172 (and hence, the plurality of magnets 188).

The magnet support member 172 may be constructed from any materialsuitable to provide adequate mechanical strength to rigidly support theplurality of magnets 188. For example, in some embodiments, the magnetsupport member 172 may be constructed from a non-magnetic metal, such asnon-magnetic stainless steel. The magnet support member 172 may have anyshape suitable to allow the plurality of magnets 188 to be coupledthereto in a desired position. For example, in some embodiments, themagnet support member 172 may comprise a plate, a disk, a cross member,or the like. The plurality of magnets 188 may be configured in anymanner to provide a magnetic field having a desired shape and strength.

Alternatively, the magnet support member 172 may be rotated by any othermeans with sufficient torque to overcome the drag caused on the magnetsupport member 172 and attached plurality of magnets 188, when present,in the cavity 170. For example, in some embodiments, (not shown), themagnetron assembly 196 may be rotated within the cavity 170 using amotor 176 and motor shaft 174 disposed within the cavity 170 anddirectly connected to the magnet support member 172 (for example, apancake motor). The motor 176 must be sized sufficiently to fit withinthe cavity 170, or within the upper portion of the cavity 170 when thedivider 194 is present. The motor 176 may be an electric motor, apneumatic or hydraulic drive, or any other process-compatible mechanismthat can provide the required torque.

Referring now to FIGS. 2-4 a prior art target assembly 200 is shown, andincludes a target 210, a backing plate 212, a grounding plate 256, a RFor DC power source 282 and a magnetron assembly 296 in a cavity 270(shown in FIG. 4). The cavity 270 is a flow volume or cavity disposedbetween the backside of the target assembly and the source distributionplate, which also includes an extended portion of a fluid inlet end 218and a fluid outlet end 220. In existing designs, this cavity correspondsto cavity 170 in FIG. 1, which is filled with heat exchange fluid for atarget 210 cooling through backing plate 212 by flowing the heatexchange fluid over backing plate 212 without channels. FIG. 3 is across-sectional view taken along line 3-3 of FIG. 2 showing fluidconduits 222 formed in cavity disposed between the backside of thetarget assembly and the source distribution plate. FIG. 3 provides asimplified cross-sectional view of the fluid conduits 222 formed betweenthe backside of the target assembly and the source distribution plate.In the configuration shown in FIGS. 2-4, the target 210 is cooled, butnot effectively because cooling water is not replaced continuously,which causes a higher target temperature, which can lead to warping,spalling of the target, particle generation and defects.

Referring now to FIGS. 5 and 6 a first embodiment of a physical vapordeposition target assembly 314, which may be integrated as the targetassembly of the PVD processing system 100 shown in FIG. 1. In theembodiment shown in FIGS. 5 and 6, the physical vapor deposition targetassembly 314 comprises a source material 313 to be deposited on asubstrate during a physical vapor deposition (or sputtering) process.The source material 313 can be a metal, metal oxide, metal alloy, or thelike. In specific embodiments, the source material comprises molybdenum.In other specific embodiments, the source material comprises silicon ortitanium or any other substance. In one or more embodiments, the targetassembly 314 includes a backing plate assembly 360 to support the sourcematerial 313. The source material 313 may be disposed on a substratesupport facing side of the backing plate assembly 360. The backing plateassembly 360 may comprise a conductive material, such as copper-zinc,copper-chrome, or the same material as the target, such that RF and DCpower can be coupled to the source material 313 via the backing plateassembly 360. Alternatively, the backing plate assembly 360 may benon-conductive and may include conductive elements (not shown) such aselectrical feedthroughs or the like.

In some specific embodiments, the backing plate 161, and when present,the cover plate 162, comprise a metal alloy having an electricalconductivity in a range of about 20-30% of International Annealed CopperStandard (IACS) and a thermal conductivity in a range of about 120-150W/mK. Examples of such a metal alloy selected from acopper-nickel-silicon-chromium metal alloy and copper-zinc metal alloycontaining lead and iron. In one or more specific embodiments, the metalalloy can comprise a Cu—Zn alloy such as C36000, which contains about60-63 weight % copper (Cu) and about 2.5-3 weight percent lead (Pb).C36000 may also contain about 0.35 weight % iron (Fe) with the remainderof the alloy containing Zinc (Zn). In other specific embodiments,Cu—Ni—Si—Cr #2 the metal alloy can comprise a Cu—Ni—SI—Cr alloy, such asCu—Ni—SI—Cr #2, which in some embodiments comprises about 87.4-91.7weight percent copper (Cu), about 6.5-8.8 weight % nickel (Ni), about1.5-2.5 weight % silicon (Si) and 0.3-1.3 weight % chromium (Cr). It hasbeen determined that when components of the assembly are fastenedtogether, the Cu—Ni—SI—Cr alloy provides specific benefits for E-beamwelding and thermal and electrical conductivity. Such an alloy providesa process and a final product in which E-beam welding of the componentsoccurs without failures such as leaks. It also decreases conductivity.

In one or more specific embodiments, the aforementioned Cu—Ni—Si—Cr orCu—Zn alloys allow for the manufacture of the backing plate by using 3Dprinting. This allows for the cover plate 162 to be eliminated and theformation of a monolithic backing plate 161 using 3D printing. Thus, inone embodiment, the backing plate 161 may be manufactured using a 3Dprinting process. In the 3D printing process, thin layers areprogressively deposited and fused until the edge of the backing plate161 is complete. Each layer is applied by a nozzle of a 3D printer in apattern stored by a 3D drawing computer program that runs on a computer(not shown). The plurality of channels 169 in the backing plate 161 maybe formed using the 3D printing process. The 3D printing approachreduces expense and time required for conventional backing plate 161manufacturing. The 3D printing process also eliminates severalconventional backing plate manufacturing steps, such as molding,casting, and machining. Additionally, tight tolerances can be achieveddue to layer-by-layer printing approach. One printing system can be usedto manufacture a variety of different backing plates, with or withoutthe plurality of channel 169, simply by changing the pattern stored inthe 3D drawing computer program. The 3D printed parts may be subjectedto post processing processes, such as hot isostatic pressing to minimizesurface defects and porosity. Such 3D printing processes are alsoreferred to as additive manufacturing (“AM”). In 3D printing processes,design data breaks the 3D object down into individual layers in twodimensional planes and the 3D object is built by adding the exact amountof material needed for each layer in an iterative manner. For thisreason, 3D printing processes can include joining or densifying thedeposited material via an energy source such as a laser, electron beam,or ion fusion melting. These techniques are capable of producing netshape, monolithic structures with intricate cavities and channels.

In one or more embodiments, the backing plate assembly 360 includes abacking plate 361. The backing plate assembly 360 may optionally includea cover plate 362 (shown in FIGS. 7A, 7B and 7C). The backing plate 361and the optional cover plate 362 may be disc shaped, rectangular,square, or any other shape that may be accommodated by a PVD processingsystem 100 as shown in FIG. 1 or other suitable PVD processing systems.A front side 370 of the backing plate 361 is configured to support thesource material 313 such that a front surface of the source material 313opposes a substrate during a PVD process. The source material 313 may becoupled to the backing plate 361 in any suitable manner. For example, insome embodiments, the source material 313 may be diffusion bonded to thebacking plate 361 or bonded with indium solder.

A plurality of channels 369 may be disposed between the backing plate361 and the cover plate 362. In one or more embodiments, the backingplate 361 may have the plurality of channels 369 formed in a backside ofthe backing plate 361 with the cover plate 362 providing a cap/coverover each of the channels, as shown in FIG. 7B. In. In otherembodiments, the plurality of channels 369 may be formed partially inthe backing plate 361 and partially in the cover plate 362 (as shown inFIG. 7C). Still, in other embodiments, the plurality of channels 369 maybe formed entirely in the cover plate 362, while the backing plate 361caps/covers each of the plurality of channels 369, as shown in FIG. 7A.

In some embodiments, the backing plate 361 and the cover plate 362 maybe coupled together. In some embodiments, the plurality of channels 369are configured to flow cooling fluid such as cooling liquid, and thebacking plate 361 and the cover plate 362 are coupled together to form asubstantially water tight or liquid tight seal (e.g., a fluid seal orliquid seal between the backing plate 361 and the cover plate 362) toprevent leakage of coolant provided to the plurality of channels 369.That is, the cooling fluid is in direct contact with the channels 369.For example, in some embodiments, the backing plate 361 and the coverplate 362 are brazed together to form a substantially water tight sealor they may be coupled by diffusion bonding, brazing, gluing, pinning,riveting, or any other fastening means to provide a liquid seal, and thechannels 369 formed between the backing plate 361 and the cover plate362 directly contact cooling fluid. In specific embodiments, the backingplate 361 and the cover plate 362 are electron beam (E-beam) weldedtogether.

One or more embodiments pertain to a method of manufacturing a physicalvapor deposition target assembly comprising forming backing plate havinga front side and a back side, the backing plate configured to support asource material on a front side of the backing plate. The method furthercomprises forming a cooling channel in the backing plate including aninlet end configured to be connected to cooling fluid, an outlet endfluidly coupled to the inlet end, and the cooling channel comprising aplurality of arcs joined together by a plurality of bends between theinlet end and the outlet end, the backing plate configured to be to coolthe source material during a physical vapor deposition process. Withreference to FIG. 9, specific embodiments comprise assembling a coverplate 162 to the back side of the backing plate 161 and electron beamwelding the cover plate and the backing plate together. Brazing paste isplaced between the backing plate 161 and the cover plate 162. Electronbeam (E-beam) welding is then utilized to fasten the backing plate 161and the cover plate 162 together. Thereafter, the fastened componentscan be heated to complete the fastening process, and then the fastenedcomponents may be machined to the final tolerance and specifications.Then the source material in the form of a target can be bonded to thebacking plate 161 or cover plate 162 with indium solder.

As mentioned above, the backing plate 161 comprises a monolithicmaterial formed by a 3D printing process in which layers of backingplate material are progressively deposited and fused to form the plateand channels. In specific embodiments in which a 3D printing process isused, there is no need for a cover plate, and the backing plate assemblycomprises a monolithic backing plate 161 and the target assembled to thebacking plate 161.

In some embodiments, such as the embodiment shown in FIG. 5 and FIG. 6,a fluid tight seal between the backing plate 361 and the cover plate 362is not necessary because the cooling fluid is contained within coolingtube 380 which is disposed within the channels 369. In otherembodiments, a cover plate 362 is not required at all, as the coolingfluid is contained within the cooling tube 380.

In a specific first embodiment, physical vapor deposition targetassembly 360 comprises a source material 313 and a backing plate 361having a front side 370 and a back side 372, the backing plate 361configured to support the source material 313 on the front side 370 ofthe backing plate 361. The first embodiment further comprises a coolingtube 380 including an inlet end 390 configured to be connected tocooling fluid, an outlet end 392 fluidly coupled to the inlet end, and aplurality of bends 396 between the inlet end 390 and the outlet end 392,the cooling tube 380 configured to be placed adjacent the back side 372of the of the backing plate 361 to cool the backing plate and the sourcematerial 313 during a physical vapor deposition process.

In a second embodiment, the cooling tube 380 is separate from thebacking plate 361 and the cooling tube provides a closed cooling loopcontaining the cooling fluid. In other words, the cooling fluid orcooling liquid is not in direct contact with the channels 369 in thebacking plate.

As discussed above, the cooling fluid can flow through the cooling tubehaving a plurality of bends, or the cooling fluid can flow throughchannels between the backing plate 361 and the cover plate 362. Ineither case, the cooling tube 380 or the channels 369 provide a fluidconduit through which cooling fluid flows and defines a fluid flowpattern. FIG. 8 shows an exemplary embodiments of a flow pattern, whichmay comprise a cooling tube 380 having a plurality of bends 396 as shownin FIG. 5 or may comprise channels formed between a backing plate 361and a cover plate 362, for example, as shown in FIGS. 7A, 7B and 7C

In FIG. 8, a flow pattern or flow path is shown comprising a pluralityof arcs 400, which in the embodiment shown, the arcs are substantiallyconcentric. In the specific embodiment shown, there are at least eightarcs 400, and a single inlet and a single outlet. In FIG. 8, an inletend 390 is fluidly connected to an inlet row 402. In FIG. 8, arc 400 aand arc 400 b form a first pair of arcs, and arc 400 c, and arc 400 dform a second pair of arcs. The first pair of arcs comprising arcs 400 aand 400 b are fluidly connected to the second pair of arcs comprisingarc 400 e and 400 f by a split connection 420. Thus, in FIG. 8, inletrow 402 is fluidly connected to the inlet end, which is fluidlyconnected to the split connection 420, which divides or splits flow ofthe fluid to the first pair of arcs comprised of arc 400 a and arc 400 band the second pair of arcs comprised of arc 400 e and 400 f. In someembodiments, the flow pattern includes arc 400 a, arc 400 b, arc 400 cand arc 400 d on a first side 401 of the inlet row 402, and arcs 400 e,400 f, 400 g and 400 h on a second side 403 of inlet row 402. Thus, thefirst side 401 includes two pairs of arcs and the second side 403opposite the first side includes two pairs of arcs. Still referring toFIG. 8, the adjacent arcs of a pair of the flow pattern are fluidlycoupled at bends. Thus, in FIG. 8, arc 400 a and arc 400 b are fluidlycoupled at bend 405, arc 400 c and arc 400 d are fluidly coupled at bend407, arc 400 e and arc 400 f are coupled at bend 409, and arc 400 g andarc 400 h are coupled at bend 411. Bend 413 fluidly couples arc 400 band arc 400 c, and bend 415 fluidly couples arc 400 f and arc 400 g.Bend 417 provides the split connection 420 that fluidly couples inletarc 402 with arc 400 d and arc 400 h. Thus, the split connection 420 isconsidered a three-way connection. In FIG. 8, the arrows indicate thedirection of fluid flowing within the arcs. Thus, fluid which may be aliquid flow through inlet end 390, along inlet row 402, to splitconnection 420, where the flow diverges in two directions, toward firstside 401 and toward second side 403. On first side, fluid flows in arc400 d in an opposite direction to the flow in inlet row 402, around bend407, and then in arc 400 c in the same direction of the flow in inletrow 402, then around bend 413 and in arc 400 b in a direction oppositeto the flow direction in inlet row 402 and around bend 405 and in arc400 a in the same direction as in inlet row 402. The fluid flows fromarc 400 a toward outlet end 392. A similar flow pattern occurs on thesecond side 403, where fluid in the form of liquid flows in thedirection shown in inlet row 402, to the split connection 420, then toarc 400 h in a direction opposite the flow direction in inlet row 402,around bend 411, then in arc 400 g in the same direction of flow as ininlet row 402, around bend 415 and to arc 400 f in a direction oppositethe flow in inlet row 402, around bend 409 and in arc 400 e in the sameflow direction as inlet row 402. The fluid flows from inlet row 402toward outlet end 392, where the fluid is then recirculated and cooledaccording to one or more embodiments. Thus, in the embodiment shown,there are at least eight arcs 400, and at least five bends, and a singleinlet and a single outlet. The inlet end and outlet end shown in theembodiment depicted in FIG. 8 can be reversed, which results in the flowof fluid in a reverse direction compared to the discussion immediatelyabove.

In a third embodiment, the first or second embodiment can be modified sothat the plurality of bends define a flow pattern includes a pluralityof arcs and the backing plate further comprises a channel in the backside configured to receive a cooling tube. In a fourth embodiment, thefirst through third embodiments are such that the plurality of bendsdefine a flow pattern including a plurality of arcs and the backingplate further comprises a channel in the back side configured to receivecooling tube.

In a fifth embodiment, the first through the fourth embodiments can bemodified so that the flow pattern comprises at least four arcs and atleast two bends. In a sixth embodiment, the first through the fourthembodiments can be modified so that the flow pattern comprises at leastsix arcs and five bends. In a seventh embodiment, the first through thefourth embodiments can be modified so that the flow pattern comprises atleast eight arcs and six bends.

In an eighth embodiment, the flow pattern comprises a first pair of arcsand a second pair of arcs, the inlet end fluidly connected to a singlearc fluidly connected to the first pair of arcs and second pair of arcsby a split connection, and the outlet end fluidly connected to the firstpair of arcs and second pair of arcs. In a ninth embodiment, the flowpattern comprises a first pair of arcs and a second pair of arcs, theinlet end fluidly connected to a single row fluidly connected to thefirst pair of arcs and second pair of arcs by a split connection, andthe outlet end fluidly connected to the first pair of arcs and secondpair of arcs.

In one or more embodiments, the cooling tube comprises a single inletend and a single outlet end. In one or more embodiments, the coolingtube comprises a single inlet end and a first outlet end and a secondoutlet end, the first outlet end fluidly connected to the first pair ofarcs and the second outlet end fluidly connected to the second pair ofarcs. In one or more embodiments, the assembly further comprises a coverplate, the cooling tube disposed between the backing plate and the coverplate. In one or more embodiments, the cooling tube or channel comprisesat least one of multiple inlet ends and multiple outlet ends. This meansthe cooling tube can have multiple inlet ends and a single outlet end, asingle inlet end and multiple outlet ends, or multiple inlet ends andmultiple outlet ends. In one or more embodiments with multiple inletends, all inlet ends may be connected to a single supply conduit or maybe fluidly connected multiple supply conduits. Similarly, in embodimentswith multiple outlet ends, all outlet ends may be connected to a singlereturn conduit or may be fluidly connected to multiple return conduits.

One or more embodiments pertain to a physical vapor deposition targetassembly comprising a source material; a backing plate having a frontside and a back side, the backing plate configured to support the sourcematerial on a front side of the backing plate; and a cover plate coupledto the backing plate, wherein channels are disposed between the coverplate and the backing plate, the channels including a plurality of bendsdefining a flow pattern including at least four arcs and at least threebends, the at least four arcs and three bends fluidly connected to aninlet end and an outlet end, the channels configured to flow coolingfluid adjacent the back side of the of the backing plate to cool thebacking plate and the target during a physical vapor deposition process.

In one or more embodiments, the channels define a flow pattern includingat least five arcs including an inlet row fluidly connected to the inletend, the inlet row fluidly connected to a first pair of arcs and asecond pair of arcs by a split connection. In one or more embodiments,the channels define a flow pattern comprising at least six arcs and fivebends. In one or more embodiments, the channels define a flow patterncomprising at least eight arcs and six bends.

In one or more embodiments, the channels define a flow patterncomprising a first pair of arcs and a second pair of arcs, the inlet endfluidly connected to a single row fluidly connected to the first pair ofarcs and second pair of arcs by a split connection, and the outlet endfluidly connected to the first pair of arcs and second pair of arcs. Inone or more embodiments, the channels are fluidly connected to a singleinlet end and a single outlet end. In one or more embodiments, thechannels are fluidly connected to a single inlet end and a first outletend and a second outlet end, the first outlet end fluidly connected tothe first pair of arcs and the second outlet end fluidly connected tothe second pair of arcs. In specific embodiments, the channels arefluidly connected to at least one of multiple inlet ends and multipleoutlet ends. This means the channels can have multiple inlet ends and asingle outlet end, a single inlet end and multiple outlet ends, ormultiple inlet ends and multiple outlet ends. In one or more embodimentswith multiple inlet ends, all inlet ends may be connected to a singlesupply conduit or may be fluidly connected by multiple supply conduits.Similarly, in embodiments with multiple outlet ends, all outlet ends maybe fluidly connected to a single return conduit or to multiple returnconduits.

In specific embodiments, tubing is disposed within said channels andfluidly connected to the inlet end and the outlet end.

Another aspect pertains to a method of cooling a physical vapordeposition target, the method comprising continuously flowing coolingfluid through the apparatus described herein.

One or more embodiments of the physical vapor deposition targetassemblies described herein can be used in a PVD processing system 100as shown in FIG. 1. In one or more embodiments, continuously flowingcooling fluid in the form of liquid through the apparatus replaces thecooling fluid such that fresh coolant fluid continuously contacts thebacking plate. Such a design advantageously has shown in modelling toprovide a significant reduction in target temperature compared tocurrent designs of the type shown in FIGS. 2 and 3. In addition, thecurved cooling channels in the form of concentric arcs provide moreuniform cooling of the source material, which minimizes the temperaturedifference across the source material, and reducing thermal stress. Inaddition, preliminary modelling data shows that with a rotating magnetdesign in a multi-cathode PVD reactor, a more uniform erosion profile ofthe source material compared to existing designs. The erosion profilewas mapped on a source material (target) in terms of heat flux using acurve fitting function.

The design described in this disclosure provides continuous replacementof cooling fluid/liquid which solves the problem of providing moreeffective and efficient heat transfer, resulting in better targetcooling and generation of fewer particles and prevention of warping ofthe target. Cooling fluid in the form of liquid such as water issupplied from one end and exits from another end of the channels afterpassing through a tortuous path, which may be a serpentine pathincluding several twists, turns and bends. The design alsoadvantageously extends the target life. These benefits were shown usingthree-dimensional conjugate modeling and comparing existing targetassembly designs with the target assembly designs described herein.

The target assemblies described herein may be particularly useful in themanufacture of extreme ultraviolet (EUV) mask blanks. An EUV mask blankis an optically flat structure used for forming a reflective mask havinga mask pattern. In one or more embodiments, the reflective surface ofthe EUV mask blank forms a flat focal plane for reflecting the incidentlight, such as the extreme ultraviolet light. An EUV mask blankcomprises a substrate providing structural support to an extremeultraviolet reflective element such as an EUV reticle. In one or moreembodiments, the substrate is made from a material having a lowcoefficient of thermal expansion (CTE) to provide stability duringtemperature changes. The substrate according to one or more embodimentsis formed from a material such as silicon, glass, oxides, ceramics,glass ceramics, or a combination thereof.

An EUV mask blank includes a multilayer stack, which is a structure thatis reflective to extreme ultraviolet light. The multilayer stackincludes alternating reflective layers of a first reflective layer and asecond reflective layer. The first reflective layer and the secondreflective layer form a reflective pair. In a non-limiting embodiment,the multilayer stack includes a range of 20-60 of the reflective pairsfor a total of up to 120 reflective layers.

The first reflective layer and the second reflective layer can be formedfrom a variety of materials. In an embodiment, the first reflectivelayer and the second reflective layer are formed from silicon andmolybdenum, respectively. The multilayer stack forms a reflectivestructure by having alternating thin layers of materials with differentoptical properties to create a Bragg reflector or mirror. Thealternating layer of, for example, molybdenum and silicon can be formedby physical vapor deposition, for example, in a multi-cathode sourcechamber.

Referring now to FIG. 10, an upper portion of a multi-cathode sourcechamber 500 is shown in accordance with an embodiment. The multi-cathodechamber 500 includes a base structure 501 with a cylindrical bodyportion 502 capped by a top adapter 504. The top adapter 504 hasprovisions for a number of cathode sources, such as cathode sources 506,508, 510, 512, and 514, positioned around the top adapter 504. The PVDprocessing system 100 described with respect to FIG. 1 can be utilizedin the multi-cathode source chamber 500 to form the multilayer stack, aswell as capping layers and absorber layers. For example, the physicalvapor deposition systems can form layers of silicon, molybdenum,titanium oxide, titanium dioxide, ruthenium oxide, niobium oxide,ruthenium tungsten, ruthenium molybdenum, ruthenium niobium, chromium,tantalum, nitrides, compounds, or a combination thereof. Although somecompounds are described as an oxide, it is understood that the compoundscan include oxides, dioxides, atomic mixtures having oxygen atoms, or acombination thereof.

Reference throughout this specification to “one embodiment,” “certainembodiments,” “one or more embodiments” or “an embodiment” means that aparticular feature, structure, material, or characteristic described inconnection with the embodiment is included in at least one embodiment ofthe disclosure. Thus, the appearances of the phrases such as “in one ormore embodiments,” “in certain embodiments,” “in one embodiment” or “inan embodiment” in various places throughout this specification are notnecessarily referring to the same embodiment of the disclosure.Furthermore, the particular features, structures, materials, orcharacteristics may be combined in any suitable manner in one or moreembodiments.

Although the disclosure herein has been described with reference toparticular embodiments, it is to be understood that these embodimentsare merely illustrative of the principles and applications of thepresent disclosure. It will be apparent to those skilled in the art thatvarious modifications and variations can be made to the method andapparatus of the present disclosure without departing from the spiritand scope of the disclosure. Thus, it is intended that the presentdisclosure include modifications and variations that are within thescope of the appended claims and their equivalents.

What is claimed is:
 1. A multi-cathode physical vapor deposition chambercomprising: a top adapter; a plurality of cathodes positioned around thetop adapter, each of the plurality of cathodes comprising a targetassembly including: a source material; a backing plate having a frontside and a back side, the backing plate configured to support the sourcematerial on the front side of the backing plate; and a cooling channelformed in the backing plate including a single inlet end configured tobe connected to a cooling fluid, a single inlet conduit and a singleoutlet having a single outlet end fluidly coupled to the single inlet,and the cooling channel comprising a plurality of arcs joined togetherby a plurality of bends between the single inlet end and the singleoutlet end, the single inlet conduit dividing a first pair of arcs on afirst side of the single inlet conduit and a second pair of arcs on asecond side of the single inlet conduit, the cooling fluid in thecooling channel configured to cool the backing plate and the sourcematerial during a physical vapor deposition process.
 2. Themulti-cathode physical vapor deposition chamber of claim 1, the targetassembly of each of the plurality of cathodes further comprising acooling tube that provides a closed cooling loop containing the coolingfluid, the cooling tube disposed adjacent the cooling channel.
 3. Themulti-cathode physical vapor deposition chamber of claim 1, theplurality of bends of the target assembly of each of the plurality ofcathodes defining a flow pattern including a plurality of concentricarcs.
 4. The multi-cathode physical vapor deposition chamber of claim 3,the flow pattern comprising at least four arcs and five bends.
 5. Themulti-cathode physical vapor deposition chamber of claim 3, the flowpattern comprising at least eight arcs and six bends.
 6. Themulti-cathode physical vapor deposition chamber of claim 3, the singleinlet end of the target assembly of each of the plurality of cathodesfluidly connected to the first pair of arcs and a second pair of arcs bya split connection, and the single outlet fluidly connected to the firstpair of arcs and the second pair of arcs.
 7. The multi-cathode physicalvapor deposition chamber of claim 3, the single inlet of the targetassembly of each of the plurality of cathodes fluidly connected to thesingle inlet conduit fluidly connected to the first pair of arcs andsecond pair of arcs by a split connection, and the single outlet endfluidly connected to the first pair of arcs and second pair of arcs. 8.The multi-cathode physical vapor deposition chamber of claim 2, thetarget assembly of each of the plurality of cathodes further comprisinga cover plate, the cooling tube disposed between the backing plate andthe cover plate.
 9. The multi-cathode physical vapor deposition chamberof claim 8, wherein the cover plate and the backing plate of the targetassembly of each of the plurality of cathodes comprise a metal alloyhaving an electrical conductivity in a range of about 20-30% ofInternational Annealed Copper Standard (IACS) and a thermal conductivityin a range of about 120-150 W/mK.
 10. The multi-cathode physical vapordeposition chamber of claim 9, wherein the cover plate and the backingplate of the target assembly of each of the plurality of cathodescomprise a metal alloy selected from a copper-nickel-silicon-chromiummetal alloy and copper-zinc metal alloy containing lead and iron. 11.The multi-cathode physical vapor deposition chamber of claim 1, whereinthe backing plate comprises a metal alloy having an electricalconductivity in a range of about 20-30% of International Annealed CopperStandard (IACS) and a thermal conductivity in a range of about 120-150W/mK.
 12. The multi-cathode physical vapor deposition chamber of claim11, wherein the backing plate of the target assembly of each of theplurality of cathodes comprises a metal alloy selected from acopper-nickel-silicon-chromium metal alloy and copper-zinc metal alloycontaining lead and iron.
 13. The multi-cathode physical vapordeposition chamber of claim 1, wherein the plurality of cathodescomprise a plurality of source materials to form a multilayer stack of afirst reflective layer and a second reflective layer and an absorber ofan EUV mask blank.
 14. A method of manufacturing an EUV mask blankcomprising depositing a multilayer stack of a first reflective layer anda second reflective layer and an absorber utilizing the multi-cathodephysical vapor deposition chamber of claim 1.